Hand-held power tool having grasp-activated power switch

ABSTRACT

A grasp-activated power switch is integrated within a handle for a hand-held power tool. The switch has an inner channel having an outer conductive layer, and a flexible outer shell having an inner conductive layer separated from the outer conductive layer by an air gap. On its surface the outer shell has actuating and non-actuating areas. A manual grasping force when applied to the actuating area flexes the inner conductive layer across the gap and electrically couples the two layers. The closure energizes an RF transmitter, which sends a pulse to a complementary receiver. With each pulse, the receiver toggles power to a motor off or on, and when on, the motor transmits power through the inner channel. When operating the tool, an operator may grasp the non-actuating area to avoid powering the tool off or on. The inner conductive layer may consist of conductive segments separated by a resilient insulator that maintains the switch open in the absence of a grasping force.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.17/235,847 that was filed on Apr. 20, 2021, which claims priority toU.S. Provisional Application 63/012,772 that was filed on Apr. 20, 2020,both of which are fully incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to power switches for hand-heldpower tools. The invention relates more specifically to agrasp-activated power switch integral to the grip of a hand-held powertool, and most specifically to such a power switch installed on a tattoomachine.

Description of Related Art

The first tattoo machine was derived from the design for an electric peninvented by Thomas Alva Edison in 1877, for which he was awarded U.S.Pat. No. 196,747. That machine used electromagnetic coils for driving areciprocating pen and needle through paper to create a perforatedpattern for autographic printing. In 1891, pioneering tattoo artistSamuel O'Reilly adapted Edison's device for tattooing by adding atubular handle for delivering ink from an ink reservoir to theperforating needle. For this design O'Reilly was awarded U.S. Pat. No.464,801.

From then til now, the basic components of a tattoo machine remainessentially unchanged. Tattoo machines all include some type of chassisadapted for hand-held operation that supports a motive force foractuating a linear motor. The motive force may be electromagnetic coils,a rotary electric motor, or a pneumatic motor. A pen coupled to themotive force draws a supply of tattooing ink to inject the ink into thedermis layer of human skin upon each stroke of the motor. Mostinnovation for tattoo machines has addressed cosmetic desires orergonomic concerns to give machines a different look and feel.

One such ergonomic advancement has been the provision of a foot pedalfor actuating, i.e. switching on or off, the power supply to the motorof a pen-style tattoo machine. While the foot pedal frees the artist'shands from having to actuate the power switch, power cable running fromthe foot pedal to the tattoo machine motor can often interfere with theartist's freedom of movement. In addition, having to maintain one footon or near the foot pedal may cause the tattoo artist to assume anawkward position while tattooing, and in general, frequent actuation ofthe foot pedal is found by many artists to cause discomfort over time.

To overcome that problem, a more recent ergonomic advantage has been theaddition of rechargeable battery packs to the chassis of the tattoomachine, made possible by recent improvements in battery technology.These battery packs are typically mounted to the end of the tattoomachine opposite the needle, which advantageously eliminatesinterference from a tethered power cord. While such battery packsprovide the artist with more freedom of movement in one sense, theyintroduce new problems that arise from placement of the power switch onthe battery pack. Because tattooing is both an operation and an art formthat requires surgical precision for finely detailed work, the artistmust use both hands in cooperation, whereby one hand (the placementhand) carefully stretches and adjusts the skin of a customer beingtattooed to achieve an optimal grip about the tattooing site while theother hand (the operating hand) holds and operates the tattoo machine.During a tattooing session, the artist must frequently start and stoppower to the tattoo machine for various reasons including cleaning theskin and conserving battery power during short breaks in the action. Butto stop or start power, the artist must remove his placement hand fromthe customer's skin to push the power switch on the battery pack, andthen reposition his placement hand to re-achieve the optimal grip. Suchaction is inefficient, time consuming, and frustrating to the artist.

For the customer, the frequent movement of the artist's placement handfrom the surface of her skin back and forth to the power supply switchcan be very disturbing, and is in fact an unsound medical procedurebecause it creates a potentially unsanitary condition. The artist'splacement hand, being in close contact with the customer's perforatedand bleeding skin, should remain isolated from all other surfaces thatcan be a potential source of infection.

What is needed is an efficient way for a tattoo artist to start and stopa hand-held battery-powered tattoo machine without having to assume anuncomfortable posture and without having to release his placement handfrom the customer's skin.

SUMMARY OF THE INVENTION

The present invention discloses an engineered design for a hand-heldpower tool having a grasp-activated power switch integrated with thegrip portion of the tool. Generally, a grasp-activated power switchaccording to the present invention allows an operator of the tool toswitch power on and off to the tool while the tool is being held in theoperator's operating hand, by squeezing the gripping portion of the toolhandle with the same operating hand. When installed for example on atattoo machine, a grasp-activated power switch according to theinvention allows a tattoo artist to maintain engagement of his placementhand at the tattooing site on a customer's skin while switching power onand off with his operating hand, without releasing his operating handfrom holding the machine. The principles of the present invention mayhave utility in applications other than tattoo machines, for example, inhand-held power tools such as medical instruments, dental instruments,high-speed drills, etc.

In a basic embodiment of the invention, a grasp-activated power switchfor a hand-held power tool includes a rigid but slightly flexible outershell having an inner conductive layer, and an inner channel having anouter conductive layer and located within the outer shell so that theouter conductive layer is electrically separated from the innerconductive layer. The inner channel is configured for attachment to thepower tool at a convenient gripping location. A wireless transmitter iselectrically coupled to one of the inner channel or the outer shell, anda battery is electrically coupled to another of the inner channel or theouter shell. The power switch is configured so that a manual graspingforce applied to the outer shell causes the outer shell to flex inward,and the inner conductive layer to electrically couple to the outerconductive layer to thereby energize the wireless transmitter byelectrically coupling the wireless transmitter to the battery.

In a more detailed embodiment, a grasp-activated power switch of theinvention includes a rigid but somewhat flexible outer shell that hasboth an actuating area and a non-actuating area. These areas aredesigned so that the manual grasping force when applied to the actuatingarea electrically couples the inner conductive layer to the outerconductive layer, and when applied to the non-actuating area does notelectrically couple the inner conductive layer to the outer conductivelayer. This feature allows the operator to manipulate or adjust thepower tool while grasping the non-actuating area to avoid undesirablytoggling the tool off and on. A more elaborate embodiment of theinvention features an inner channel that is generally cylindrical inform, and defines a hollow longitudinal space concentrically alignedwithin the inner channel. The hollow longitudinal space allows passagetherethrough of a moving shaft or other energizable element of the powertool.

To create the actuating and non-actuating areas on the outer shelf, theinvention may include an inner channel having a proximal shelf and adistal shelf, and an outer conductive layer on the inner channel thatextends between the proximal shelf and the distal shelf. Both theproximal shelf and the distal shelf are concentrically aligned with theinner channel, and one or both of the shelves has a diameter greaterthan a maximum width of the outer conductive layer. The differencebetween the greater diameter and the maximum width of the outerconductive layer defines a gap that electrically separates the innerconductive layer from the outer conductive layer. The non-actuating arealies above one of the two shelves, and the actuating area lies adjacentto the non-actuating area between the two shelves, where the graspingpressure can force the conductive layers into contact.

In another embodiment of the invention, a grasp-activated power switchserves as a handle of a hand-held power tool. The power switch includesan inner channel having an outer conductive layer, and an outer shellsurrounding the inner channel, the outer shell having an innerconductive layer, an actuating area, and a non-actuating area. The powerswitch is configured such that a manual grasping force when applied tothe actuating area electrically couples the inner conductive layer tothe outer conductive layer, and when applied to the non-actuating areadoes not electrically couple the inner conductive layer to the outerconductive layer. The power switch may further include a battery and awireless transmitter electrically coupled to the battery and to one ofthe inner conductive layer or the outer conductive layer, and configuredfor wireless coupling to a wireless receiver mounted elsewhere on thepower tool. The power switch is configured so that the manual graspingforce when applied to the actuating area causes transmission of powerwithin the inner channel.

Another embodiment is a tattoo machine having a linear motor, a batterypack mounted on a proximal end of the machine and configured to energizethe linear motor, and a shaft coupled to the linear motor and configuredfor attachment to a tattoo needle at the distal end of the machine,improved by a handle coupled between the proximal and distal ends of themachine, the handle including a grasp-activated power switch accordingto the present invention. The grasp-activated power switch includes anouter shell having an inner conductive layer, and an inner channelhaving an outer conductive layer and located within the outer shell sothat the outer conductive layer is electrically separated from the innerconductive layer, wherein the inner channel defines a hollowlongitudinal space for passage of the shaft therethrough. Thegrasp-activated power switch is configured so that a manual graspingforce when applied to the outer shell electrically couples the innerconductive layer to the outer conductive layer to switch power off or onto the machine without obstructing movement of the shaft. A wirelesstransmitter is electrically coupled to one of the inner channel or theouter shell, and a battery is electrically coupled to another of theinner channel or the outer shell, so that the manual grasping forceapplied to the outer shell energizes the wireless transmitter byelectrically coupling the wireless transmitter to the battery. Thetattoo machine may further include a wireless receiver configured toreceive a wireless signal transmitted by the wireless transmitter, andin response to receiving the wireless signal cause energization of thelinear motor by the battery pack.

In any of various embodiments of a grasp-activated power switchdisclosed herein, the outer conductive layer of the inner channel of thepower switch may include a plurality of conductive segments. Each of theconductive segments may be spaced apart from an adjacent one of theconductive segments by a resilient insulator. The conductive segmentsmay each be formed as a ring, wherein all such rings are electricallycoupled as a singular node, or the conductive segments may be a singlecontinuous wire conductor wrapped spirally around the resilientinsulator. The resilient insulator has a diameter slightly greater thanthat of the conductive segments to maintain the switch as an opencircuit in the absence of a grasping force applied to the outer shell.When a grasping force is applied to the outer shell, the innerconductive layer of the outer shell compresses the resilient insulatoruntil one or more conductive areas of the inner conductive layer makeelectrical contact with a conductive segment to close the switch.

BRIEF DESCRIPTION OF THE DRAWINGS

Other systems, methods, features and advantages of the invention will beor will become apparent to one with skill in the art upon examination ofthe following figures and detailed description. It is intended that allsuch additional systems, methods, features and advantages be includedwithin this description, be within the scope of the invention, and beprotected by the accompanying claims. Component parts shown in thedrawings are not necessarily to scale, and may be exaggerated to betterillustrate the important features of the invention. Dimensions shown areexemplary only. In the drawings, like reference numerals may designatelike parts throughout the different views, wherein:

FIG. 1 is a side view of one embodiment according to the invention of agrip for a hand-held power tool having an integral grasp-activated powerswitch.

FIG. 2 is a transparent and partially exploded side view of the grip ofFIG. 1.

FIG. 3 is a partially cutaway side view of the grip of FIG. 1.

FIG. 4 is a distal end view of the grip of FIG. 1 with cap portionremoved.

FIG. 5 is a perspective view of the cap portion of the grip of FIG. 1.

FIG. 6 is a perspective view of another embodiment according to theinvention of a tattoo machine having an integral grasp-activated powerswitch.

FIG. 7 is a frontal view of the tattoo machine of FIG. 1.

FIG. 8 is an exploded frontal view of the tattoo machine of FIG. 1.

FIG. 9 is an exploded frontal view of the distal end of the tattoomachine of FIG. 1, showing an outer shell and inner channel.

FIG. 10 is a perspective view of the outer shell of a tattoo machinehaving an integral grasp-activated power switch according to theinvention.

FIG. 11 is a distal end perspective view of an inner channel of a tattoomachine having an integral grasp-activated power switch according to theinvention.

FIG. 12 is a proximal end view of an inner channel for one embodiment ofa grasp-activated power switch according to the invention.

FIG. 13 is a perspective view of one embodiment of a battery pack for atattoo machine having an integral grasp-activated power switch accordingto the invention.

FIG. 14 is a circuit diagram showing electrical connections in the griparea for one embodiment according to the invention for a hand-held powertool having an integral grasp-activated power switch.

FIG. 15 is a circuit diagram showing electrical connections in thebattery pack area for one embodiment according to the invention for ahand-held power tool having an integral grasp-activated power switch.

FIG. 16 is a cross-sectional view of one embodiment according to theinvention for a grasp-activated switch when a grasping force is appliedto a non-actuating area.

FIG. 17 is a cross-sectional view of one embodiment according to theinvention for a grasp-activated switch when a grasping force is appliedto an actuating area.

FIG. 18 is a transparent and partially exploded side view of analternative embodiment of the invention for a grasp-activated powerswitch having a segmented outer conductive layer.

FIG. 19 is an exploded frontal view of a distal end of a tattoo machineequipped with a grasp-activated power switch according to thealternative embodiment of the present invention.

FIG. 20 is a distal end perspective view of an inner channel in anintegral grasp-activated power switch according to the alternativeembodiment for use with a tattoo machine according to the invention.

FIG. 21 is a cross-sectional view of an alternative embodiment accordingto the invention for a grasp-activated switch having a segmented outerconductive layer, shown when a grasping force is applied to anon-actuating area.

FIG. 22 is a cross-sectional view of an alternative embodiment accordingto the invention for a grasp-activated switch having a segmented outerconductive layer, shown when a grasping force is applied to an actuatingarea.

DETAILED DESCRIPTION OF THE INVENTION

The following disclosure presents exemplary embodiments for systems andmethods that employ an integral grasp-activated power switch for ahand-held power tool according to the present invention. Thegrasp-activated power switch allows an operator of the tool to turn thetool on and off by squeezing the grip once to turn on and again to turnoff, in toggling fashion. As used throughout this disclosure, the term“grasp-activated” means causing the operation of an electrical switch bya squeezing or clamping action of the operator's hand on a handle orgrip portion of the power tool being switched. A grasp-activated actionis therefore not accomplished by pushing a button, turning a dial, or bytwisting, pushing, or pulling a lever. A grasp-activated action isaccomplished by forcing together two opposing sides of a grip or handleby an operator squeezing the grip or handle between his thumb andforefinger.

The present invention applied to tattoo machines improves the comfort,posture, and ease of tattooing for the tattoo artist, and also improvesthe means for actuating the tattoo machine power supply. The inventionallows the artist's operating hand (i.e. the hand that holds themachine) to activate the battery by turning it on and off with a squeezeof the grip for a more seamless tattooing experience. The principles ofthe present invention may have utility in applications other than tattoomachines, for example, in hand-held power tools such as medicalinstruments, dental instruments, high-speed drills, etc., especiallywherever the tool operator performs high-precision work that requiresfrequent stopping and restarting of the power tool.

The invention gives tattoo artists the ability control the power switchof the tattoo machine very easily, when necessary to stop and grab ink,paper towels, or other accessories. The invention is particularly usefulwhen an artist suddenly becomes aware that a supply of ink in an ink caphas run low, because it allows the artist to very easily stop the tattoomachine to prevent the needle from impacting the bottom of the ink cap.Also, about every hour or so, a tattoo artist needs to stop work, standup, and stretch and with the present invention this can be more easilydone. Enhanced power control provided by the grasp-activated grip of thepresent invention allows the artist to minimize battery powerconsumption, minimize the likelihood of contaminating the needle, andminimize the risk of accidental injury by puncture from a tattoo needle.

According to the invention, actuation of the grasp-activated switch canconnect the tattoo machine motor to the main battery either bydirectly-coupled wire, or wirelessly by means of an RF or Bluetooth™transmitter coupled to the grasp-activated switch. Such a wirelesstransmitter is configured to communicate with a complementary wirelessreceiver that is coupled to the main battery. The present invention maybe integrated into a grip alone, for removable installation on existingtattoo machines or other tools, or the invention may be integrated aspart of an entire hand-held power tool system.

FIG. 1 shows a side view of one embodiment according to the invention ofa grip 20 for a hand-held power tool having an integral grasp-activatedpower switch. The grip 20 includes an outer thin plastic wall or shell 1that provides a gripping surface that allows an operator to manuallygrasp and control the tattoo machine during operation. A seam 2 isdefined between the distal end of the outer shell 1 and a distal end cap4. The distal end cap 4 is removably attachable to the distal end ofshell 1, and may include one or more grooves, protrusions, orindentations 3 that are formed on an outer surface of the end cap 4, asin the example shown, to enable the operator to more easily manuallyattach or detach the end cap 4 to or from the outer shell 1. An opening5 at the proximal end of the outer shell 1 provides a means forconnecting the grip to a motive force and power supply for energizingthe tool.

The outer shell 1 has dual-purpose utility: first, it provides agripping surface to allow an operator to grasp the tool firmly by onehand, i.e. between thumb and forefinger, while directing andmanipulating the tool; and second, it provides a manually operable, orgrasp-activated, switch that allows the operator to switch power on andoff to the power tool while grasping the tool. In particular, the outershell 1 is configured with both a non-actuating area and an actuatingarea. In the embodiments illustrated herein, the non-actuating areaoccurs at the distal end of the outer shell, and the actuating areaoccurs away from the distal end of the outer shell, at or near themiddle portion of the outer shell, for example. This configurationallows the operator to grasp the outer shell at the non-actuating areaand operate the tool without causing the tool to switch on or off, orslightly adjust his grip and grasp the outer shell at the actuating areawhere he can switch power to the tool on or off by gently squeezing theouter shell 1 between his thumb and forefinger.

To enable the dual-purpose utility of the outer shell 1, the outer shell1 is preferably formed from a rigid but slightly resilient material suchas a thermoplastic—ABS, nylon, polycarbonate, polyethylene, etc.—or froma thin metal sheet such as steel or aluminum that will allow for slightflexing. In another embodiment, a hard synthetic rubber may be used toform the outer shell. When used for tattoo machines or on medical ordental instruments, an advantage provided by the invention is the optionto design the outer shell 1 to be disposable, for sanitary purposes.Thus, longevity of service life may not be an essential design basis, sothat less expensive materials of construction can be selected for theouter shell.

FIG. 2 shows a transparent and partially exploded side view of the grip20. In this view, the distal end cap 4 is shown partially detached fromthe grip 20 to reveal threads 11 that illustrate one possible means forremovably attaching the distal end cap 4 to the grip 20. The transparentview reveals that the outer shell 1 has an inner conductive layer 6disposed onto its inner surface. In the embodiment shown herein, theouter shell 1 is generally cylindrical, and the inner conductive layer 6also forms a generally cylindrical inner wall. The inner conductivelayer may be the inner surface of an outer shell 1 that is composed ofmetal. Or the inner conductive layer 6 may be a thin metal sheetmaterial curved into a cylindrical form and attached to a non-metallicinner surface of the outer shell 1, or the inner conductive layer 6 maybe a pre-formed cylindrical metal pipe, or it may be a portion of aconductive metal sheet, pipe, or other material attached to anon-conductive material that forms part or all of the outer shell 1.

The grip 20 also includes an inner channel 8 that is concentricallyaligned with the outer shell 1. A hollow longitudinal space 22 runsthrough the center of the inner channel 8 from proximal opening 5 todistal opening 12. The inner channel 8 may also be generally cylindricalin form, and has an outer conductive layer 21 on its outer surface thatis displaced from the inner conductive layer 6 by a gap 7. Gap 7 may beon the order of about 0.036 inches in width, although greater and lessersuch widths are certainly possible within the scope of the invention.And while the embodiment of grip 20 disclosed herein has a generallycylindrical form, with generally cylindrical conductive layers 6 and 8,other geometric configurations are possible within the scope of theinvention that maintain a gap 7 of a desired width. The desired width ofthe gap 7 is a distance sufficient to prevent electrical current flowacross the gap when the grip is not being squeezed when the tool iselectrically energized, but that also provides good electrical contactbetween conductive layers 6 and 21 when the actuating area of outershell 1 of the electrically energized tool is being squeezed with manualforce.

To maintain the form and integrity of the grip 20, the inner channel 8is formed from a rigid material that is generally not flexible and willnot deform under a manual gripping force. Materials such as metal orhard plastic are suitable for forming the inner channel 8. To create thenon-actuating and actuating areas of the outer shell 1, a proximal shelf9 and a distal shelf 13 are formed on respective ends of the innerchannel 8. The shelves 9 and 13 are similarly formed from rigidmaterials, and may be integral to the inner channel 8, or rigidlyattached thereto. The outer shell 1 spans over both the proximal shelf 9and the distal shelf 13. Preferably, shelves 9 and 13 are made from adielectric material, with one or both of the shelves 9 or 13 having aconductive outer surface. In the embodiments shown herein, the proximalshelf 9 has a dielectric surface and the distal shelf 13 has aconductive surface. When the grip 20 is in the “shelf” position, thatis, resting on a shelf or otherwise in a condition not being grasped orsqueezed by an operator's hand, the conductive surface of the distalshelf 13 is electrically separated from the outer conductive layer 21 onthe inner channel 8. Also while in the shelf position, the innerconductive layer 6 of the outer shell 1 forms a conductive bridge overshelves 9 and 13. In the shelf position, the inner conductive layer 6may contact the conductive surface of the distal shelf 13 and thedielectric surface of shelf 9, but does not contact the outer conductivelayer 21, being separated therefrom by the gap 7. The non-actuating areaof the outer shell 1 therefore occurs at or near the distal end of theouter shell, where pressure between the operator's thumb and forefingerwill force the inner conductive layer 6 against the conductive surfaceof the distal shelf 13, but not deform the outer shell 1 to cause anypart of the inner conductive layer 6 to close the gap 7 and make contactwith the outer conductive layer 21 of the inner channel 8. Accordingly,the actuating area of the outer shell 1 occurs a short distance awayfrom the distal end of the outer shell 1 at an intermediate locationbetween the proximal shelf 9 and distal shelf 13, where pressure betweenthe operator's thumb and forefinger will slightly deform the outer shell1 and force the inner conductive layer 6 into electrical contact withthe outer conductive layer 21 of the inner channel 8, thereby closingthe grasp-activated switch.

The inner channel 8 may include complementary means for removablyreceiving the distal end cap 4. In this example, such receiving meanscomprises female threads formed on the distal end of the inner channel 8and sized to engage with male threads on the distal end cap 4. Anopening 12 is defined through the distal end cap 4, to accommodate thedistal end or working element of the power tool, e.g., a saw blade,drill bit, or the needle end of a tattoo machine. Opening 12 passes allthe way through the longitudinal center of grip 20 to the proximalopening 5 to allow the grip 20 to be installed on the power tool and toallow the working element at the distal end of grip 20 to be coupled tothe motor of the power tool at the proximal end of grip 20.

FIG. 3 shows a partially cutaway side view of the grip 20. This viewreveals electronic components that are mounted to the inner channel 8and that make up a portions of the electrical circuit of thegrasp-activated power switch. These components include a circuit board,a battery 17, and wiring 15, 16, 18. The circuit board includes an RFtransmitter 14. The battery 17 provides power to the transmitter 14.Battery 17 may consist of multiple batteries ganged in series and/orparallel to achieve a desired voltage. Each such battery may be lithiumion type or another known type of battery technology, disposable orrechargeable. In one example, battery 17 consists of a single 3.7-Vlithium ion disposable battery. In another example, battery 17 consistsof three 1.5-V batteries.

In FIG. 3, the battery 17 is mounted to the distal shelf 13. In otherembodiments, the battery 17 may be mounted to the distal end cap 4, tothe outer shell 1, or to another location on grip 20. Wiring 15electrically couples the positive terminal of the transmitter 14 to theouter conductive layer 21 of the inner channel 8. Wiring 16 electricallycouples the positive terminal of battery 17 to the inner conductivelayer 6 of the outer shell 1. Wiring 18 connects the negative terminalof the transmitter 14 to the negative terminal of battery 17 to completethe circuit, so that when a sufficient manual grasping force squeezesgrip 20 to make electrical contact between the inner conductive layer 6and the outer conductive layer 21, the grasp-activated switch closes andas a result transmitter 14 is energized by the battery 17. See FIG. 16.

When the transmitter 14 is energized, it transmits an on/off signal orpulse to a complementary receiver 24 that is mounted on or near the mainpower supply for energizing the motor of the hand-held tool. Forexample, where the hand-held tool is a tattoo machine, the main powersupply may be a main battery pack mounted at the proximal end of themachine. In this way the main battery back is configured for wirelesscommunication with the transmitter 14. When the receiver 24 receives theon/off signal, it causes a switch at the output of the main battery packto change state, using any of numerous flip-flop type logic circuitswell known in the electrical engineering arts. That is, if the mainbattery pack switch was off when the on/off signal is received, itchanges state to on, and if the battery pack switch was on when theon/off signal is received, it changes state to off. In this manner anoperator of the hand-held tool using a grip 20 according to the presentinvention can toggle power off and on to the motor of the tool bymomentarily squeezing the actuating area of outer shell 1 with hisoperating hand that is already grasping the grip 20.

One advantage of using the combination wireless transmitter 14 andreceiver 24, rather than hard-wiring the grasp-activated switch to theterminals of main power supply, is to provide a disposable part that canbe easily installed onto the hand-held tool with no effect on thewiring. For example, after a tattooing session, the operator candisconnect the end cap 4, pull the grip 20 (consisting of the shell 1and inner channel 8) off the distal end of the tool, and discard thegrip 20 as medical waste. Another advantage of the wireless switch is toavoid having to run wiring in close proximity to moving parts of thetool, which is especially useful when using the grasp-activated switchof the present invention as an after-market modification to acommercially available tool. In other embodiments of the invention,however, the grasp-activated switch may be hard-wired to the main powersupply of the tool, to reduce the overall manufacturing cost of thegrip, and possibly increase reliability by eliminating the need for thebattery 17.

FIG. 4 shows a distal end view of the grip 20 with distal end cap 4removed. This view shows wiring 18 that couples the negative terminal ofbattery 17 to the negative node of the transmitter 14. In oneembodiment, the grip 20 may include a dielectric core 19 between theinner channel 8 and the hollow longitudinal space 22 that runs throughthe center of the inner channel 18 from proximal opening 5 to distalopening 12. The dielectric core 19 adds strength and rigidity to thegrip, and may be made from a resilient material to assist the grip inrestoring itself to original form when an operator's grasping force isreleased. In one embodiment, the dielectric core 19 may be formed froman epoxy. In another embodiment, the dielectric core 19 may comprisesilicone. In another embodiment, the dielectric core may providestructural support and insulation to one or more electrical componentsof the grip 20. In one example, the transmitter 14, battery 17, andassociated wiring and/or circuit boards may be embedded within thematerial of the dielectric core during manufacture while the core is inliquid or gel form prior to setting.

The hollow longitudinal space 22 runs through an interior wall 23 thatis concentrically aligned with the longitudinal axis of the innerchannel 8. Space 22 is configured to allow the working end of thehand-held tool to pass through the grip 20 unobstructed. The interiorwall 23 is formed from a rigid material configured to engage one or morebearings or other components that support a shaft of the motor of thehand-held tool. The interior wall 23 has sufficient strength to resistdeformation when an operator squeezes the outer shell 1, so that tooloperation is unobstructed during the transition of power from off to onor vice versa.

FIG. 5 shows a perspective view of the distal end cap 4 of the grip 20,to illustrate threads 11 that surround the opening 12. The threads 11may be configured to engage complementary threads formed on the distalend of the interior wall 23. The end cap 4 may assume a variety ofshapes, depending on the configuration of the working end of the tool.Ideally, when the end cap 4 is fully engaged to the interior wall 23, atight seal is formed at seam 2 to insulate the electronic componentsfrom contamination. An advantage provided by the threaded or removableengagement of the end cap 4 to the outer shell 1 is to facilitate quickreplacement of a the outer shell 1 along with its interior parts,particularly in applications wherein the outer shell 1 and its interiorparts are designed to be a disposable, consumable item. To protectagainst the spread of infection among tattoo customers, a removablyengageable outer shell portion 1 of the grip 20 as described herein canbe made to be disposable and easily replaced, so that each tattoocustomer can be treated with a tattoo machine affixed with a new andsterile grasp-activated grip or sleeve.

FIG. 6 shows a perspective view of another embodiment according to theinvention. In this embodiment, the hand-held tool that bears thegrasp-activated power switch is a tattoo machine 60. Tattoo machine 60is a commercially available machine that is modified by installing agrip 20 of the present invention as an after-market modification. Anouter shell 1 of the grip 20 is shown in the figure. A batterycompartment 62, also modified according to the invention, is connectedto the proximal end of the tool 60. An end cap 4 is attached to thedistal end of the tool 60, to protect a reciprocating tattoo needledriven by a linear motor that is enclosed within a motor casing 64. Agrip 63, provided by the original tattoo machine manufacturer, allows auser to grasp the machine 60 while operating it; however, grip 63 is astatic device that does not provide a grasp-activated switch. FIG. 7shows a frontal view of the tattoo machine 60. Several additionaloptional features are shown on the battery compartment 62. These includea manual on/off pushbutton 65, a voltage up/down toggle switch 66, anLED display 67, and a lid 68. FIG. 8 shows an exploded frontal view ofthe tattoo machine 60. This view reveals the proximal end of the linearmotor 69 that lies within the motor casing 64, and also the distal end70 of the machine as provided by the original tattoo machinemanufacturer.

FIG. 9 shows an exploded frontal view of the distal end of the tattoomachine 60. This view illustrates two main components of the inventionthat are used in the modification of machine 60—the outer shell 1 andthe inner channel 8. Threading on interior wall 23 may be used by anoperator to adjust the length of protrusion of a tool element, such as atattoo needle 26, beyond the distal end of the end cap 4. While makingthis adjustment, with the machine fully assembled as shown in FIG. 7,the operator may grasp the outer shell 1 of grip 20 at its non-actuatingarea A1 and press the outer shell 1 against the distal shelf 13, thenrotate the end cap 4 with respect to the grip 20. In this manner, theadjustment can be made without switching the machine on or off.

FIG. 10 shows a perspective view of the outer shell 1 of the tattoomachine 60. The inner conductive layer 6 is shown on the inner surfaceof the outer shell 1. FIG. 11 shows a distal end perspective view of aninner channel of a tattoo machine having an integral grasp-activatedpower switch according to the invention. The dielectric core 19 madefrom epoxy or silicone fills the void between inner channel 8 and thehollow longitudinal space 22. Various electronic components and wiringmay be embedded within the core 19. FIG. 12 shows a proximal end view ofan embodiment of an inner channel 8.

FIG. 13 is a perspective view of one embodiment of a battery pack 62 fora tattoo machine having an integral grasp-activated power switchaccording to the invention. Battery pack 62 includes one or moreindividual batteries 73 arranged as a pack in a series or parallelconfiguration to achieve a desired voltage needed to drive the machine'sDC motor, usually 7.5V to 8.5V for a tattoo machine. The manual on/offswitch 65 is bypassed so that the on/off switching operation can beperformed by an electric circuit provided on a circuit board 74 that ismounted within the battery pack 62. The circuit board 24 includes areceiver 24 that is configured to receive and respond to an RF signalfrom the transmitter 14 that is mounted to the grasp-activated switch20. Other components on circuit board 24 are shown in the circuitdiagram of FIG. 15.

FIG. 14 is a circuit diagram 140 that shows typical electricalconnections in the grip area for one embodiment according to theinvention for a hand-held power tool, such as a tattoo machine, havingan integral grasp-activated power switch. Wiring 16 connects thepositive terminal of battery 17 to the inner conductive layer 6. Theouter conductive layer 21 is connected by wiring 15 to the positiveterminal of the RF transmitter 14. The negative terminal of transmitter14 is connected by wiring 18 to the negative terminal of battery 17.When an operator squeezes the actuating area of the outer shell 1, theinner conductive layer 6 is pressed into electrical contact with theouter conductive layer 21 to close the switch and complete the circuit.This action energizes the transmitter 14, which sends a momentary RFpulse wirelessly to receiver 24 that is mounted in the battery pack onthe proximal end of the tool. The operator need only squeeze the gripmomentarily to switch the power on or off to the tool. A subsequentsqueeze will cause the tool to change state again, either from on to offor off to on.

FIG. 15 is a circuit diagram 150 showing electrical connections in thebattery pack area for one embodiment of a hand-held power tool, such asa tattoo machine, having an integral grasp-activated power switch. TheRF receiver 24 is configured to receive and respond to the RF pulsetransmitted by transmitter 14. The response of the receiver 24 is togenerate a pulse, such as a voltage spike of about 5 volts, across itsterminals using methods known in the art. The pulse is fed to an inputpin of an integrated circuit (IC) 71 that is configured as a toggleswitch flip-flop. For example, an IC 4017 may be used for this purpose,by connecting pin #4 to pin #15 so that each successive pulse at theinput toggles the output between 0 and +5V. The toggling output pin iscoupled to the base 75 of a transistor 72 configured to behave as asolid state switch. Transistor 72 will therefore change state with eachsuccessive pulse, alternately enabling and disabling current flow to arelay 74 that is magnetically coupled to a normally open switch. Whencurrent flows through transistor 72, relay 74 is energized, closing theswitch that provides power from batteries 72 to the tool motor, such aslinear motor 69 described in a previous embodiment. When current throughtransistor 72 is cut off, relay 74 de-energizes and the switch opens tostop the motor. Circuits 140 and 150 can thereby perform the samefunction as the manual on/off pushbutton switch 65, to allow an operatorto toggle the tool on and off. But unlike switch 65, an operator usingthe present invention can toggle the power by momentarily squeezing thegrip.

FIGS. 16 and 17 are a cross-sectional views of one embodiment accordingto the invention for a grasp-activated switch 160. Switch 160 is similarin form and function to the grasp-activated switch described within grip20 as shown in FIGS. 1-5. FIG. 16 illustrates the configuration ofswitch 160 when a grasping force F1 is applied to a non-actuating areaA1. FIG. 17 illustrates the configuration of switch 160 when a graspingforce F2 is applied to an actuating area A2. In general, thenon-actuating area A1 of the switch occurs at the distal end of theassembly on and about the area where the outer shell 1 covers the distalshelf 13. In one embodiment, the non-actuating area occurs approximatelyalong the “distal third” of the grip. The actuating area A2 of theswitch occurs along an area proximally adjacent to area A1, along themiddle area of the outer shell 1. In one embodiment, the actuating areaA2 occurs along about twice the length of the non-actuating area A1. Inother embodiments, the size, length, and location of areas A1 and A2 mayvary, depending on tool type, size and other design considerations. Inanother example, the proximal shelf 9 may be made conductive andseparated from the outer conductive layer 21, and the distal shelf 13may be made non-conductive, so that the distal-to-proximal locations ofareas A1 and A2 are reversed, with A2 located on the distal side of A1.

In FIG. 16, a grasping force F1 is applied to the non-actuating area A1.This action has no effect on the grasp-activated switch, and so theswitch remains open, with gap 7 separating inner conductive layer 6 fromouter conductive layer 21. An operator may grasp the outer shell 1 inthis manner while operating or adjusting the tool.

In FIG. 17, the operator changes the state of the grasp-activated switchby momentarily adjusting his grip on the outer shell 1 to place histhumb and forefinger within the actuating area A2 and squeezing theouter shell 1 with a quick, firm pulse. This action drives the innerconductive layer 6 across the gap 7 into electrical contact with theouter conductive layer 21, thereby completing the circuit, e.g. as shownby the switch in circuit 140. As described in the context of circuits140 and 150, the grasping pulse of the operator at area A2 causes achange of state in the operation of the power tool, from on to off orfrom off to on.

Alternative Embodiment—Spiraled Outer Conductive Layer

FIG. 18 shows a transparent and partially exploded side view of analternative embodiment 80 for a grasp-activated power switch accordingto the invention. In the alternative embodiment 80 (also referred toherein as grip 80), the smooth or continuous sheet of conductivematerial that forms the outer conductive layer 21 for grip 20 isreplaced by a plurality of outer conductive layer segments 81. All othernumbered parts of the grip 80 function as in the aforedescribed contextof grip 20.

In the exploded side view of grip 80, each exposed segment 81 of theouter conductive layer is separated from an adjacent segment by aresilient insulator 82. In one implementation, the segments 81 of theouter conductive layer are formed as a single continuous ribbon or wireconductor that is wrapped spirally around the resilient insulator 82, tocreate a spiraled outer conductive layer 81. In another implementation,the segments 81 of the outer conductive layer are formed as a series ofconcentrically arranged rings that are each spaced apart from anadjacent segment 81 by a resilient insulator 82 and that are allelectrically coupled as a singular node. For example, the ringedsegments 81 may be interconnected by conductive tabs or wire runningthrough the resilient insulator 82 or on an interior side of theresilient insulator 82. The resilient insulator 82 may be formed from asingle piece of dielectric material such as rubber or plastic, or it mayconsist of a plurality of noncontiguous rings of insulation. In general,the ringed or spiraled segments 81 of the outer conductive layer aresubstantially concentrically arranged along with the rings of theresilient insulator 82.

In addition, in any implementation of the alternative embodiment forgrip 80, the rings of the resilient insulator 82 have a slightly greaterdiameter than the rings or spiraled segments 81 of the conductive outerlayer. For example, in one embodiment, the difference “delta” indiameter between spiraled segments 81 and resilient insulator 82 may beon the order of the thickness of a standard sheet of paper, or betweenabout 0.07 mm and 0.13 mm. In another embodiment, delta has a maximumvalue of 1.0 mm. In another embodiment, delta has a mean value of about0.05 mm or 0.002 inches. The greater diameter of the resilient insulator81 maintains the switch as an open circuit in the absence of a graspingforce applied to the outer shell 1. When a grasping force is applied tothe outer shell 1, the inner conductive layer 6 of the outer shell 1compresses the resilient insulator 82 until one or more conductive areasof the inner conductive layer 6 make electrical contact with aconductive segment to close the switch. When the grasping force isreleased, the resiliency of the resilient insulator 82 pushes the innerconductive layer 6 back to its original position to open the switch.

FIG. 19 shows an exploded frontal view of a distal end of a tattoomachine equipped with a grasp-activated power switch according to thealternative embodiment 80 of the present invention. This view shows theouter shell 1 and an inner channel 88 insertable within the outer shell1. The inner channel 88 includes a segmented outer conductive layerrepresented by the rings or spiral segments 81. Each of the rings orspiral segments 81 is spaced apart from an adjacent ring or spiralsegment 81 by a resilient insulator 82. All numbered parts of the grip80 may have form and function as previously described.

FIG. 20 shows a distal end perspective view of the inner channel 88 inan integral grasp-activated power switch according to the alternativeembodiment 80 for use with a tattoo machine according to the invention.The inner channel 88 includes a segmented outer conductive layer 81 andthe resilient insulator 82, and additional numbered parts of the innerchannel 88 that may have form and function as previously described.

FIGS. 21 and 22 show a cross-sectional views of one embodiment accordingto the invention for a grasp-activated switch 180. Switch 180 is similarin form and function to the grasp-activated switch 160, except that thesmooth or continuous sheet of conductive material that forms the outerconductive layer 21 in switch 160 is replaced by a plurality of outerconductive layer segments 81 and a resilient insulator 82. The resilientinsulator 82 has a slightly greater diameter than any diameter of thesegments 81, as shown. Resilient insulator 82 may be a singular piece ofdielectric material, or may consist of a plurality of rings ofdielectric material. All other numbered parts of the grip 80 function asin the aforedescribed context of grip 20. FIG. 21 illustrates theconfiguration of switch 180 when a grasping force F1 is applied to anon-actuating area A1. FIG. 22 illustrates the configuration of switch180 when a grasping force F2 is applied to an actuating area A2.Operation of switch 180 is similar to that of switch 160, such that whenthe grasping force F1 is applied to area A1, the switch 180 forms anopen-circuit, with a gap 7 entirely separating the inner conductivelayer 6 from each of the conductive segments 81 of the outer conductivelayer; and such that when the grasping force F2 is applied to area A2,the switch 180 forms a closed circuit, with one or more contact areas 83of the inner conductive layer 6 making electrical contact with one ormore conductive segments 81 of the outer conductive layer.

To ensure good electrical contact between the inner conductive layer 6and an outer conductive segment 81 under force F2, the inner conductivelayer 6 should be made of a thin, flimsy conductor that is deformablewhen pressed by hand. Examples of material for the inner conductivelayer 6 include copper and aluminum foil or sheet, or a deformableconductive fabric, having a thickness of about 1 mm or less. Whenpressed, the inner conductive layer 6 impacts the outer perimeter of oneor more of the resilient insulators 82, compressing the resilientinsulator and temporarily reducing its diameter to about the samediameter as that of an adjacent outer conductive segment 81. Thiscompression allows one or more contact areas 83 to be pushed betweenadjacent resilient insulators 82 to make contact with a conductivesegment 81. An advantage of the configuration of conductive segments 81(whether coupled rings or spiraled conductor) separated by resilientinsulators 82 is that it allows the designer to form the outer shell 1from a thinner, flimsier material such as an inexpensive plastic orsynthetic rubber or metal sheet. Generally, fabrication costs will beless expensive and the design more suitable for making the outer shell 1and its internal components disposable. The alternative embodiments ofgrip 80 and switch 180 may thus be used effectively for a wide range ofinstruments that come into contact with a human body and need to be keptsterilized, such as medical instruments, dental instruments, tattoomachines, motorized massage tools, barber tools, and the like. Usage ofthe invention is also appropriate on non-medical tools, such ashand-held drills, saws, screwdrivers, sanders, etc., and especially formotorized hand-held tools operated in confined spaces.

Exemplary embodiments of the invention have been disclosed in anillustrative style. Accordingly, the terminology employed throughoutshould be read in a non-limiting manner. Although minor modifications tothe teachings herein will occur to those well versed in the art, itshall be understood that what is intended to be circumscribed within thescope of the patent warranted hereon are all such embodiments thatreasonably fall within the scope of the advancement to the art herebycontributed, and that that scope shall not be restricted, except inlight of the appended claims and their equivalents.

What is claimed is:
 1. A grasp-activated power switch for a hand-heldpower tool, comprising: an outer shell having an inner conductive layer;an inner channel having an outer conductive layer and located within theouter shell so that the outer conductive layer is electrically separatedfrom the inner conductive layer, the inner channel configured forattachment to the power tool; a wireless transmitter electricallycoupled to one of the inner channel or the outer shell; and a batteryelectrically coupled to another of the inner channel or the outer shell;whereby a manual grasping force applied to the outer shell causes theinner conductive layer to electrically couple to the outer conductivelayer thereby energizing the wireless transmitter by electricallycoupling the wireless transmitter to the battery.
 2. The grasp-activatedpower switch of claim 1, wherein the outer shell includes an actuatingarea and a non-actuating area, such that the manual grasping force whenapplied to the actuating area electrically couples the inner conductivelayer to the outer conductive layer, and when applied to thenon-actuating area does not electrically couple the inner conductivelayer to the outer conductive layer.
 3. The grasp-activated power switchof claim 1, wherein the inner channel has a generally cylindrical form.4. The grasp-activated power switch of claim 3, wherein the innerchannel defines a hollow longitudinal space concentrically alignedwithin the inner channel.
 5. The grasp-activated power switch of claim4, wherein the hollow longitudinal space allows passage therethrough ofa moving shaft of the power tool.
 6. The grasp-activated power switch ofclaim 5, wherein the inner channel further comprises a proximal shelfand a distal shelf, and wherein the outer conductive layer extendsbetween the proximal shelf and the distal shelf.
 7. The grasp-activatedpower switch of claim 6, wherein one or both of the proximal shelf andthe distal shelf is concentrically aligned with the inner channel. 8.The grasp-activated power switch of claim 7, wherein one or both of theproximal shelf and the distal shelf has a diameter greater than amaximum width of the outer conductive layer.
 9. The grasp-activatedpower switch of claim 8, wherein the difference between the diameter ofone or both of the proximal shelf and the distal shelf and the maximumwidth of the outer conductive layer defines a gap that electricallyseparates the inner conductive layer from the outer conductive layer.10. The grasp-activated power switch of claim 9, wherein the gapcomprises a hollow cylindrical space having a thickness of about 0.036inches.
 11. The grasp-activated power switch of claim 1, wherein theouter conductive layer of the inner channel comprises a plurality ofconductive segments.
 12. The grasp-activated power switch of claim 11,wherein each of the conductive segments is spaced apart from an adjacentone of the conductive segments by a resilient insulator.
 13. Thegrasp-activated power switch of claim 12, wherein the conductivesegments comprise a single continuous wire conductor wrapped spirallyaround the resilient insulator.
 14. The grasp-activated power switch ofclaim 12, wherein the plurality of conductive segments form a maximumdiameter of the outer conductive layer, and wherein the resilientinsulator has a greater diameter than the maximum diameter of the outerconductive layer.
 15. The grasp-activated power switch of claim 11,wherein each of the conductive segments comprises a ring, and whereinall of the conductive segments are electrically coupled as a singularnode.
 16. A grasp-activated power switch serving as a handle of ahand-held power tool, the power switch comprising: an inner channelhaving an outer conductive layer; and an outer shell surrounding theinner channel, the outer shell having an inner conductive layer, anactuating area, and a non-actuating area; such that a manual graspingforce when applied to the actuating area electrically couples the innerconductive layer to the outer conductive layer, and when applied to thenon-actuating area does not electrically couple the inner conductivelayer to the outer conductive layer.
 17. The grasp-activated powerswitch of claim 16, further comprising: a battery; and a wirelesstransmitter electrically coupled to the battery and to one of the innerconductive layer or the outer conductive layer, and configured forwireless coupling to a wireless receiver mounted to the power tool. 18.The grasp-activated power switch of claim 16, wherein the manualgrasping force when applied to the actuating area causes transmission ofpower within the inner channel.
 19. The grasp-activated power switch ofclaim 16, wherein the outer conductive layer of the inner channelcomprises a plurality of conductive segments.
 20. The grasp-activatedpower switch of claim 19, wherein each of the conductive segments isspaced apart from an adjacent one of the conductive segments by aresilient insulator.